貉肠炎沙门菌htra基因缺失株的构建及其生物学特性

Construction and biological characteristics identification of htra gene knock-out mutant of raccoon Salmonella enteritidis

利用Red同源重组方法对HtrA蛋白编码基因htra进行敲除,并从生长特性、生化特性、耐pH应激与氧化应激、抗血清杀伤和菌株毒力等几方面对突变菌株进行评价。结果显示,与野生型菌株相比,htra基因缺失株生长特性和生化特性无明显差异,但其对酸性和碱性环境的敏感性增加,对血清的耐受力下降;动物试验结果显示,htra基因缺失后肠炎沙门菌对小鼠半数致死量有显著提高。本试验成功构建了貉肠炎沙门菌htra基因缺失株,为研究HtrA蛋白的作用机制奠定了基础。

HtrA plays a critical role in bactreial growth and survive under various stress conditions, and knockout of htra gene leads to sharply attenuated virulence in Escherichia coli. To investigate the roles of HtrA protein from Salmonella enteritidis ,isolated from raccoon,in biological characteristics and virulence. The htra mutant of Salmonella enteritidis was constructed by ）,-Red homologous recombination,and comparison of growth characteristics, biochemical characteristics, anti-stress of pH,survival in serum and bacterial virulence were performed between wild type strain and htra mutant. The data demonstrated that,the mutant showed no difference in growth characteristics and biochemical characteristics with wild type strains. But compared to the wild type strains,the mutant displayed increased sensitivity to pH stress and serum. And the htra mutant showed increased LD50 ,indicating the deficient virulence of mutant. In this study, we successfully constructed the htra gene-deleted mutant of raccoon Salmonella enteritidis, providing foundation for exploring underlying mechanism of HtrA protein.